The present application relates generally to registering a first image device with a second image device. More particularly, the present invention relates to an apparatus and a method for determining a relative positional and rotational offsets between a first and second imaging device of a wavefront system.
Laser eye surgical procedures typically employ some sort of system that may measure the optical characteristics of the patient's eye. One promising eye measurement system is the VISX WaveScan™ System, which uses a Hartmann-Shack wavefront sensor assembly that may quantify higher-order aberrations throughout the entire optical system, including first and second-order sphero-cylindrical errors and third through sixth-order aberrations caused by coma and spherical aberrations. The wavefront measurement of the eye creates a high order aberration map that permits assessment of aberrations throughout the optical pathway of the eye, e.g., both internal aberrations and aberrations on the corneal surface. Thereafter, the wavefront aberration information may be saved and thereafter input into the laser system to compute a custom ablation pattern to correct the aberrations in the patient's eye.
The WaveScan™ System also includes a camera (“pupil camera”) that takes images of the eye at the time the wavefront measurements are taken with the Hartmann-Shack wavefront sensor assembly. The images of the eye taken with the pupil camera may be used to track the spatial position of the eye so as to properly align the ablative laser with the eye during the corneal ablation treatment.
Because the tracking and alignment of the eye during the laser ablation is based on the image taken with the pupil camera, it is important that the wavefront data is spatially aligned, both translationally and rotationally, with the image taken with the pupil camera. If the pupil camera and wavefront sensor are not spatially aligned when the wavefront measurements are obtained, the subsequent laser assisted corneal ablation, which relies on the wavefront measurements, may not be properly registered with the patient's eye.
Consequently, what are needed are devices and methods which may determine a relative positional and rotational offset between the two imaging devices of the wavefront system.